This invention relates to tractor trailers and particularly to a safety device for a fifth wheel arrangement to eliminate jackknifing. The invention however has broader application and the principles thereof may be incorporated on any towed vehicles.
One of the most serious safety problems encountered in the trucking industry involves the jackknifing of tractor trailer rigs. Jackknifing usually occurs on high speed highways where there is a panic stop particularly when the wheel brakes do not lock at the same time. This action often results in overturning of either or both the tractor and the trailer.
Jackknifing is generally caused by abrupt turns, skids or sway of the tractor trailer such that the momentum of the towed vehicle is in a different direction from the towing vehicle. The resultant jackknifing occurs when one or both of the vehicles are thrown off the line of travel into a sideways skid.
The prior art discloses many arrangements to prevent jackknifing in tractor trailers but there is no disclosure of the unique and advantageous arrangement of the present invention. Among the closer prior art patents, U.S. Pat. No. 4,120,514 to Sanders includes a single forward slotted portion and a single hydraulically actuated pin. The foregoing patent fails to disclose the particular slot arrangement herein with reciprocable pins engaging slots on both sides of a downwardly projecting king pin.
U.S. Pat. No. 4,241,934 to J. F. Buehner discloses a cooperating stop lug and limit stop in an anti-jackknife device with the lug being fluid actuated. U.S. Pat. No. 3,733,090 to A. T. Keller illustrates a further improvement in anti-jackknifing assemblies for trucks involving retractable members which engage stopping blocks on opposite ends of arcuate paths defined on the towed vehicle.
U.S. Pat. No. 4,204,700 to J. R. Haines, Sr. includes a pair of slots in a bed plate with downwardly projecting elements to engage said slots and associated holes in a fifth wheel to eliminate jackknifing. U.S. Pat. No. 3,353,841 is also of interest in this area as are other references but none of the prior art appears to possess the distinct advantages of the present invention which will be discussed hereinafter in the specification.